1. Field of the Invention
The present invention generally relates to electrical contacts and elements and their surfaces and physical properties, and especially to electrical light bulbs and to electrical sockets. More particularly it relates to 3-way electrical light bulbs and their electrical sockets and related components. The invention also relates to 3-way light sockets, whether they incorporate a switch or not. The invention further relates to washers or devices or inserts or adapters in general that can be used in conjunction with such light bulbs and/or their sockets.
2. Background of the Invention
Reference to a Related Article
The January 2002 issue of “DESIGNFAX” Magazine had, in page 64, an interesting article that triggered my thoughts towards the inventions covered by this application.
The article in question was entitled: “Side Jobs”, or “Problem of the Month”. I have copied it and am attaching it as “Additional Documents” at the end of this application. A photocopy of the articles is shown in page LS-A-2. It is not quite legible. So, I scanned the article and with OCR, I created a “text” version of it and I am showing it in page LS-A-1.
The gist of the article is the problems that are found with 3-way light bulbs and their sockets. These sockets are referred to sometimes as light sockets and other times as lamp sockets. Most of the sales packages of such sockets, on the market, refer to them as lamp sockets. So, in this specification I will most often use the term “lamp socket” or simply “socket”.
The referenced article states the following complaint.
“Recently, one of our staffers posed this problem to us. Why is it, he asked, that they can't make a decent three-way light bulb? It seems that all four 3-way lamps in his house are afflicted with flicker—that is, when switched to the lowest or highest output, the light tends to blink on and off.
Adjust the contacts? Yes, he's cleaned and adjusted the contacts of the sockets of all the lamps (unplugged from the wall first, of course), as well as sanding and cleaning of the bulbs. In frustration he's just installed single-wattage bulbs into the fixtures—obviously a solution, but it does offer a challenge. So we ask you for suggestions, not just for our staffer's immediate illumination needs, but also for alternative designs that won't require the complete overhaul of existing light-bulbs and can be done for a low cost.”
Personal Verification
I, the inventor, remembered that occasionally I, too, had the same “flicker” problem with some of my 3-way light lamps in my house.
However, I wanted to verify that the problem really existed. So I talked to a friend of mine, whose name is Ed V.E. Ed is an electrician and teaches the trade to aspiring electricians at a local college. At one time, Ed was working with a large local company and was responsible for the maintenance operation, especially the electrical side of the operation. That company owned a few hotels, among other things. Ed told me the following.
Yes, there is a problem with 3-way electrical light bulbs and their sockets. It was so bad, that at one time, some companies have tried to solve the problem, but have given up. He remember that Phillips and Duro-Test had offered some solutions, but they were either too expensive or did not get enough appeal or acceptance from the market.
One solution was very expensive compared to regular 3-way light bulbs. The “improved” bulbs was “guaranteed for long life”, but their cost was prohibitive.
Another solution was to provide the light bulb with a wavy spring instead of the solid ring. But for some reason, this solution did not work either. Not successful. Did not last long on the market.
Ed recalled also that they were telling the maids, at the company's hotels, not to tighten the light bulbs into the sockets too tightly. But that did not help either. It seems that the maids noticed the flicker. So, they thought that the bulb was not seated properly. So, they went and tried to tighten the bulb more in the socket, and they often broke the bulbs.
Then, I did a small market search.
This is what I discovered.
Potential Problem Sources
I discovered basically THREE potential sources for the problem:                1. The bulbs have a problem, but by themselves and on their own, they are OK.        2. The sockets have a problem, but by themselves and on their own, they are OK.        3. The system, or the combination of, using such bulbs and sockets creates problems. It is mainly the orientation or correlation of the threads in the bulbs and sockets together with the presence of the solder spot 19 of the bulb that create the problems.Potential Problem Source #1: The bulbs have, or could cause, a problem.        
The problem is the way the middle contact ring 3 of the bulbs is manufactured. Here is what I mean. The bulbs, as shown in FIGS. 1 & 2, are made with the standard center contact point 1, like the standard one-way bulbs, also known as “one-wattage bulbs, plus a middle contact ring 3, that is located between the center contact point and the outside bulb threaded metal base 5, that acts as the return terminal. Insulations 7 and 9 are in-between for proper electrical separation.
The bulb middle contact ring 3 is connected to the middle filament 11 inside the glass body 13 of the bulb 15 by soldering the filament wire 11 or the filament carrying wire 17 to the bulb middle contact ring 3. The solder joint 19 is usually pretty rough, bumpy and out of plane with respect to the bulb middle contact ring 3 itself, i.e. it is higher than the rest of the surface of that bulb middle contact ring 3. It protrudes over the surface of the bulb middle contact ring 3 and it creates an uneven contact surface. Sometimes, it protrudes as high as 0.030 inch or higher, over the surface of the bulb middle contact ring 3.
So, when a person inserts such a bulb into the socket 21 in FIG. 3 and turns it in, and “reaches bottom”, the contact elements inside the socket would touch the corresponding contact points of the bulb. First, you make contact between the center points and then you make contact between the middle contacts. I will explain what occurs at this time, in a moment.
Potential Problem Source #2: The sockets have, or could cause, a problem.
The 3-way sockets have three contact elements that touch three corresponding elements of the bulb.
FIG. 3 shows a cross-section view of such a 3-way bulb sitting inside a 3-way socket. FIG. 4 shows a close-up view of the socket. FIGS. 5 and the subsequent figures show an even larger close-up view.
When a light bulb is properly seated in the socket, the following three pairs of elements are making contact.
1. The bulb threaded metal base 5 is touching the socket threaded shell 27.
2. The center contact point 1 of the bulb is touching the center contact spring 23 of the socket. Actually, the socket center contact spring 23 is applying a certain contact force against the bulb center contact point 1, pushing the bulb threaded metal base 5 upwards against the thread of the socket threaded shell 27, by an equal amount of force.
3. The bulb middle contact ring 3 is touching the socket middle contact element 31.
How Present Bulbs and Sockets Work
I will describe how they work, in three different steps, as follows. I will use FIGS. 1 through 8. While doing this, I will also point out the potential sources of problems, and possibly mention briefly some suggestions for corrective action. I will then elaborate later on these suggestions.    A-HOW 1-WAY (SINGLE-WATTAGE) BULBS WORK IN THEIR SOCKETS    B-HOW 3-WAY BULBS WORK IN THEIR SOCKETS    C-HOW THE 3-WAY SOCKETS THEMSELVES WORK.1. How 1-Way (Single-wattage) Bulbs Work in Their Sockets
Now, I will first describe the standard one-way bulb and its corresponding socket, and how they interact. Then I will compare them with the 3-way bulb and socket.
The sockets for standard one-way bulbs have only one contact spring, the socket center contact spring 23, in the center of the socket, which is similar to the center contact spring 23 of the 3-way socket, to make contact with the center point 1 of the bulb, which again is similar to the 3-way bulbs from this respect. They do not have the “stop” 31, which we see in the 3-way sockets. The return current goes through the bulb threaded metal base 5 to the socket threaded shell 27 of the socket. This is similar to the 3-way sockets. The center contact element 23 of the socket 21 is a “spring”, as I said. When a person threads a bulb into the socket, one of two things can happen. First, if the power is already turned on, then when the bulb is threaded in far enough for the bulb center contact point 1 to reach the socket center contact spring, the light would turn on, and most probably the person would stop and leave the bulb at that position. It is not the ideal thing to do. If the bulb is wiggled slightly, there could be a good chance of getting some flicker, because the socket center contact spring may separate from the bulb center point 1. The second thing that can happen is that the person would thread the bulb in a little bit more. This would be advisable. But when would you stop? Most of the time, you would stop when you feel enough resistance to the threading process. You could keep on threading the bulb in, all the way, until the bulb has bottomed down all the way into the socket. This is probably the best way. At this situation, the socket center contact spring 23 would be compressed all the way down and would be seated on top of the bottom part 29 of the socket. This should not harm the contact spring because the spring should still have enough springiness (flexibility) in it to work with this bulb or any other replacement bulb that may be inserted later in the same socket.
So far so good, for standard one-way bulbs. But now let us compare this with the 3-way bulbs and their sockets.
2. How 3-Way Bulbs Work in Their Sockets
The 3-way sockets 21 have two contact elements beside the return, instead of only one in the 1-way sockets. The first contact element is the center contact spring 23. This is exactly like the one for the standard one-way sockets as mentioned above. The second contact element is what I call the socket middle contact element 31. And this is the one part that creates the major part of the problem, as far as I can see.
The socket middle contact element 31 of all the 3-way sockets that I have found in the market is “RIGID”. It is not springy like the center contact spring. It seems the manufacturers of these sockets wanted to use this MC as a “STOP”. This is my interpretation of the existing design and the thought process behind it.
The way I see it, this is what happens.
When you thread the 3-way bulb into the socket, you first make contact with the center points, i.e. bulb center contact point 1 with socket center contact spring 23, as I said before. You may or may not get the light on, if you have the power on. Officially you should not have the power on, when you are inserting the bulb in the socket. It is dangerous. It can create a spark, which could cause harm. So, you would not know whether you made any contact or not yet. So, you keep threading the bulb in further until you feel some appreciable resistance. This is most probably when the middle contact ring 3 of the bulb touches the socket middle contact element 31 of the socket. This is the time when your luck can be very important. If you hit the socket middle contact element 31 with a point on the bulb middle contact ring 3 that does not have the solder joint 19 on it, or near it, you should be OK. But, if the solder joint 19 just happens to be near the area where you are touching the socket middle contact element 31, then you may hit a high spot at one instant and then you may hit a low spot at another instant. The change can be just a slight change in turning the bulb or some other change due to temperature or whatever. Basically you create an “unstable” electrical contact, and that is the bad news. Another possibility is that if you have threaded the bulb in just enough to make electrical contact, but “mechanically” the contact (touching) is not strong enough, the electrical resistance at the contact area can be relatively high. This could create some localized heating, which in turn could create some expansion and contraction at the local contact area and that can create havoc with the system.
This is my interpretation of the problem. Also based on my experience with connector and interconnection device, I would not design a connector or a socket with such a rigid contact element. It is simply not done, as far as I know.
3. How the 3-Way Sockets Themselves Work
FIG. 1 shows the basics of the 3-way light bulb, with the filaments and the filament carrying wires “simplified” for clarity of illustration.
FIG. 2 shows a close-up view of the lower portion of the same bulb.
FIG. 3 shows a cross-section of the socket, with a bulb in it.
FIG. 4 shows an enlarged view of the lower portion of FIG. 3.
FIGS. 5 through 8 show an even closer view of the main mechanism of the socket and the base of the bulb with the different contact elements of both. They also show the four different positions of the switch that controls which filament will be turned on or off, at any of these four positions. I will explain.
FIG. 5 shows the position of the switch cam 41, which I will refer to also as the rotating cam 41, when no filaments are on. The light is OFF.
FIG. 6 shows the position when the “middle filament” 11 is ON. The power is connected from the switch hot wiper 43 through the rotating cam 41, to the switch middle wiper 45, and then from it to the “RIGID” socket middle contact element 31, which touches bulb middle contact ring 3. Then the power flows from there to the middle filament 11 and then back to the bulb threaded base 5 and from it to socket threaded shell 27. So, the result is that the middle filament 11 will be turned ON.
Please note that the rotating cam 41 has four cam surfaces, cam surface B 49, cam surface C 51, cam surface D 53, and cam surface A 55. The rotating cam 41 itself is made of an insulating material. So, if any contact element is touching cam surface A 55, then no electrical power can be conveyed to it.
However, each of the other three cam surfaces, i.e. cam surface B 49, cam surface C 51, cam surface D 53 are covered by a metallic surface, which is connected to a metallic plate 57, shown in dotted lines, in the back of the rotating cam 41. So, these three cam surfaces are connected electrically to each other.
Consequently, in this position in FIG. 6, the switch hot wiper 43 is connected to cam surface B 49, which in turn is connected to cam surface D 53 through the hidden metallic plate 57, which then is connected to switch middle wiper 45.
FIG. 7 shows the position when the “center filament” 10 is ON. The power is connected from the switch hot wiper 43 through the rotating cam 41, through cam surface C 51, the hidden metallic plate 57, cam surface B 49, to the switch center wiper 59, which is integral with the “springy” socket center contact spring 23, which touches the bulb's Center Contact Point 1. Then the power flows from there to the center filament 10 and then back to the bulb threaded metal base 5 and from it to the socket threaded shell 27. So, the result is that the center filament 10 will be turned ON.
FIG. 8 shows the position when both the “center filament” 10 as well as the “middle filament” 11 are ON. The power is connected from the switch hot wiper 43 through the rotating cam 41 through cam surface D 53 and hidden metallic plate 57, to the switch center wiper 59 as well as to the switch middle wiper 45 through cam surface D 53, hidden metallic plate 57, cam surface B 49, and then from there to the two bulb filaments 10 and 11, as described above. So, the power flows through both filaments 10 and 11, which then will be turned ON.
In all these four figures, we can see that the socket center contact spring 23, which is a springy contact, can operate through a large arc. At its highest position 61, marked “F”, the contact spring is under no load. This position is called the FREE position of the spring, hence the letter “F”. If the spring is compressed all the way down, it will be seated against the bottom 29 of the socket, hence the letter “S” for this position 63. Usually the bulb is threaded down until it is seated on the socket middle contact element 31, which seems to also act as the “STOP”. In this position, the socket center contact spring 23 is at its “acting” position 65, hence the letter “A”.
NOTE: Hence, we will use the following legend:
“F” means the FREE shape of any spring.
“A” means the ACTING shape or position of any spring.
“S” means the SEATED shape or position of any spring.
Discussion Re the Socket Middke Contact Element 31
The purpose of this part, and the effect of the fact that it is rigid.
The socket center contact spring 23 has a wide range of acceptable positions, practically from position F 61 through position S 63, FIGS. 1 through 8. Ideally, the operating position 65 of the spring should be somewhere close to the center of its range. The way it is shown here in all the figures is pretty good.
This socket central contact spring can be considered as an ideal electrical contact spring. The reasons are: 1) It has a wide range of elastic travel. When it is fully seated, i.e. pushed as far down as it can go, it does not undergo any permanent plastic deformation, i.e. once released, it goes back to its original free position, hence it does not loose its force-deflection curve characteristics. 2) When the bulb is threaded in, the spring applies a force that is relatively constant. It is a relatively soft spring, and its force-deflection curve is relatively flat. This means the force magnitude remains roughly the same, for slight changes in the position of the bulb.
Compare this with the socket middle contact element 31 below.
The socket middle contact element 31 is a rigid mechanical part. You may have noticed that I keep referring to it as an “element”, not as a “spring”. In reality, every mechanical part can be considered as a spring. When a force is applied to any mechanical part, it will flex to some extent. But under the same amount of force, we can intuitively see that a member like the socket middle contact element 31 would deflect an infinitesimal amount, compared with the deflection of a member like socket center contact spring 23 under the same amount of force. So, for all practical purposes, we can safely say that socket middle contact element 31 is not a spring, but is a rigid body.
The way I see it, the original purpose of the socket middle contact element 31 seems to be two-folds. First and foremost, it is supposed to function as an electrical contact. And incidentally, it is also supposed to function as a mechanical stop, I guess. I personally do not see the need to have a mechanical stop, because the bulb can safely be threaded in all the way until the central spring is fully seated against the floor 29 of the socket. This is what happens with the single wattage light bulbs. They do not have and do need an additional element to act as a stop. So, why would a 3-way bulb need one? So, if the sole purpose of socket middle contact element 31 is to act as an electrical contact spring, then a better design is needed. And this is what I am offering here by this invention.
What happens when we thread a light bulb in such a socket against this socket middle contact element 31. If the bulb is pushed tightly against it, by threading/turning it tightly, then the top surface of socket middle contact element 31 starts to rub and scratch the surface of the bulb middle contact ring 3. The socket middle contact element 31 would not deflect like the socket center contact spring 23. It would stand its ground. What would give in is the softer surface of the bulb middle contact ring 3. The socket middle contact element 31 may dig in and create a slight grove in bulb middle contact ring 3. This can continue until the resistance against further turning the bulb becomes too great, so we stop turning. This is fine. What we get in this case is two things. First, the scratching and digging exposes clean base metal on both surfaces of socket center contact spring 23 and socket middle contact element 31 and creates a good electrical connection. At the same time, it creates a stable mechanical connection, where the two parts are “locked-in” and would not be unlocked unless forcefully done so. Such a locked-in mechanical situation makes for a mechanically stable connection, and a relatively permanent one. Thus, the electrical contact in this case would be good and acceptable and it would work for a long time.
However, once in a while, we get the elevated rough uneven solder spot 19 in the picture. If the orientation of the thread on the base of the bulb, and the orientation of the socket threaded shell 27, and the circumferential position of the solder spot 19, all work in some strange way, we would end up having the solder spot 19 hit socket middle contact element 31 while we are just about ready to make the electrical/mechanical contact with it (socket middle contact element 31). It is like when the stars line up once in a while. If that happens, then we have a problem. This is what happens.
The solder spot 19 would hit the socket middle contact element 31 against its side, not along its upper surface. This is because the solder spot 19 is higher than it adjacent ring surface. This would prevent the bulb from turning any further. The user would feel the resistance against turning, so he would stop turning any further, thinking that he has done a good job inserting/installing the bulb into the socket. In fact, there is a “temporary” mechanical as well as an electrical contact at that moment, but in reality it is an unstable contact because the mechanical contact is unstable. It is not “locked-in”, as compared to the previous situation described above. There is not enough friction or other restrains that would ensure that the solder spot 19 would remain in that position forever. Any slight disturbance may “dislodge” the spot from this position and would push it away from socket middle contact element 31. If that happens, then we would get an open electrical circuit and the electrical current/power would be interrupted and the light would go off. The disturbance could move the spot away from socket middle contact element 31 just temporarily or permanently. If it were temporary, then it would be a worse case. Because the electrical power would be interrupted for a short moment and the light would go off, and then the disturbance would push the spot back against the socket middle contact element 31 and the power and light would go on again. This may repeat often enough and we would get the undesirable “flicker”. This disturbance could be a vibration from any outside source or could be due to temperature fluctuation or any other source. The disturbance does not need to be extremely large. Even a few thousandth of an inch movement could result in such an undesirable result. Again, the reason is that the contact between the spot and socket middle contact element 31 is not a “stable” one, as explained above. The connection is not locked-in mechanically, so it is unstable and unreliable.
In contrast, if we do the same thing with a contact spring, like socket center contact spring 23, and we move the bulb by similar distances, the electrical current flow would hardly be affected at all. The contact spring, being elastic, would “follow” the bulb and would still exert/apply approximately the same amount of contact force, thus maintaining the required conditions for a good electrical connection. We would not get any interruptions in the current flow and the light would stay on and would not flicker.
Back to the Problem
So, the problem, as explained above, is with the rigidity of socket middle contact element 31 of the socket, in conjunction with the elevated uneven surface of the solder spots 19 of the bulbs and their position on the bulb middle contact ring 3.
Please note that if the socket is used by itself, then there is no problem. It works OK. Similarly, if the bulbs are used by themselves, then again there is no problem. They would work. However, when you use them together, then the problems arise.
If we look at FIGS. 5 through 8, we notice the solder joint 19 represented by the irregular blob at the left side of the bulb middle contact ring 3. It is shown at that position simply for illustration purposes. In reality, we do not know where it ends up, when the bulb is threaded into the socket. It can be exactly at the position shown, or it can end up right on top of socket middle contact element 31, or anywhere in between. If it happens to end up close to SM, then we can expect some difficulties, as explained above. In other words, if this happens, then we could get an intermittent contact, i.e. the electrical power may not be steady. It may be readily interrupted, thus creating the “flicker”, or the contact resistance could be high, creating a hot spot, etc.
To repeat then, one source of potential problem is the fact that socket middle contact element 31 is rigid. This can be a problem, regardless of where the solder joint 19 ends up. During the operation of the bulb and socket system, the elements of the system gets exposed to varying temperatures. The result is that the elements change temperature and consequently expand or contract accordingly. Any such changes can force the contact elements to get closer to each other, which is not too bad. On the other hand, the contact elements could get farther apart. This is where trouble starts. We would get what could be considered an open circuit. Or at least, it could be a high resistance contact condition. In either case, the power could become discontinued or lowered because of the open circuit or the high resistance. This can manifest itself as the dreaded “flicker”.
A Personal Experiment
To determine the Location of the Bulb Solder Spots 19 with respect to socket middle contact element 31.
I have purchased five 3-way light bulbs at random from a local store. I have inserted each one of them into one and the same 3-way socket, and threaded them down until I hit “bottom”, i.e. until I felt enough resistance against threading in the bulb any further.
I have marked the rotational location 73 of each bulb with respect to a specific point on the socket. See the black mark 71 on the thread of the bulb, as shown in FIG. 75.
In FIGS. 76 and 77, the five bulbs, 71, 75, 79, 83 and 87, are positioned with their black marks, 73, 77, 81, 85 and 89, roughly in the same angular position, namely facing the viewer. It can be seen that the solder spots 19 of each of the five bulbs, on bulb middle contact ring 3, are not in the same comparable angular positions. They are distributed randomly around the ring, as follows:
Bulb #171 has the solder spot 19 spread from around 2 o'clock to around 5+o'clock.
Bulb #275 from around 3 o'clock to around 5+o'clock.                Bulb #379 from around 12 o'clock to around 2+o'clock.        Bulb #483 from around 9 o'clock to around 10+o'clock.        Bulb #587 from around 8 o'clock to around 9 o'clock.        
Obviously, the bulbs are not consistent, as far as the angular location of the solder spot 19 with respect to the thread on the bulb base 5 is concerned.
Out of these five bulbs, one bulb ended up with the solder spot 19 hitting the rigid middle contact/stop element 31 of the socket. You may notice that I will refer to the socket middle contact element 31 also as the “stop 31” or the socket middle stop 31. This created an interference. It prevented the bulb from being rotated any further. The bulb simply hit the stop 31 and stopped rotating. It is because the high shape of the solder spot 19 hit the side of the stop 31, instead of its top contact surface, as it should do. This prevented the bulb from rotating any further. This type of “touching” could be considered a false contact condition and makes for an unstable contact and could create “flicker”.
Although this has not been a statistically rigorous experiment, still one out of five bulbs proving defective is a high percentage (20%) of defects among this small sampling.
Prior Art
As far as I know, there has never been any prior art covering anything similar to the concepts offered in this present invention. I am not aware of any. I am sorry; I could not find any.
In the following specifications I will propose some solutions that could help.